Dictionaries & sets
Key–value maps, uniqueness, counting, grouping, and fast lookups.
How to Diff Two Dicts in Python: Added, Removed, and Changed Keys
Compare two dictionaries and report added, removed, and changed keys using Python's set operations on dict keys.
def diff_dicts(old: dict, new: dict) -> dict:
"""Compare two dicts and report added, removed, and changed keys."""
added = {k: new[k] for k in new.keys() - old.keys()}
removed = {k: old[k] for k in old.keys() - new.keys()}
common_keys = old.keys() & new.keys()
changed = {k: (old[k], new[k]) for k …How to Find Symmetric Difference Between Two Python Sets
Compute elements unique to each set and build a flag dictionary showing membership across two Python sets.
def symmetric_difference_with_flags(set_a, set_b):
"""Return elements in either set but not both, grouped by which set they came from."""
only_in_a = set_a - set_b
only_in_b = set_b - set_a
print(f"Only in A: {only_in_a}")
print(f"Only in B: {only_in_b}")
print(f"Symmetric difference: {onl…Browse by section
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Dictionaries & sets — Python code examples
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This page collects dictionaries & sets snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
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